1. Field of the Invention
The present invention relates to a flexible joint, intended to join two elements, and to facilitate changes in the angular orientation of said elements in relation to each other.
2. Description of the Prior Art
In several fields of use, it is desired to join elements in relation to each other in such a way, that the angular relationship of said elements in relation to each other can be changed. Examples of such fields of use are tiltable masts, which are arranged tiltable in relation to a supporting base, crane jibs, having one or several points arranged flexible in the direction of extention, and a number of mechanical designs including flexible links, having angular positions in relation to each other arranged changable.
Previously known designs for the above purpose usually include a pivoting joint, for example with a pin joining the members, and further including means for positioning of the elements in relation to each other, and said additional means may include hydraulically or pneumatically operated cylinder members, co-acting screw and pinion, or similar. For these solutions it is necessary, that a "hinged connection" can be arranged at the flexible location, is that said elements can be arranged pivotable in relation to each other, said previously mentioned additional means only being used for changes in the angular relationship of the elements in relation to each other.
For applications in which the elements for example comprises two tubular members, having adjacently located end portions in close contact when arranged extending linearly in relation to each other in a first position, there are considerable problems to accomplish a flexible joint using conventional techniques. The necessary "hinged connection" must be arranged outside or adjacent to the outer edge portion of each element, if a pivoting movement should be accomplished. Such an external flexible joint is obviously both aesthetically and economically undesirable, but has previously been regarded as necessary, for example when two tubular members in a first position of extension are to be arranged with facing end portions in abutment, and when this position of extension should be adapted to be changed into a second position of extension, in which said abutment is no longer maintained. This problem is further accentuated if two tubular members in a first and linear position of extension are arranged in an each other embracing position, that is when one element has an end portion with such an internal diameter that it can be located embracing adjacent end portion of the second element. If two such elements should be arranged to facilitate positioning in a different angular relationship to each other, the element must first be separated by means of a linear sliding movement, before a pivoting movement can be performed. It is obviously possible to accomplish such a joint using conventional techniques, for example by means of hydraulically or pneumatically operable cylinder members, one being arranged to accomplish the preliminary linear sliding movement, whereafter a second cylinder member can be used to accomplish a pivoting movement. However, it is also necessary to use specially designed joining members to maintain a "hinge acting" connection during the above described movement. It is obvious, that such a design requires considerable space, but also is costly from manufacturing point of view, and that it also requires access to a hydraulical or pneumatical pressure medium. The complicated design also requires regular servicing, and the risk for malfunction is also obvious.